4O OUR NATIVE FERNS AND THEIR ALLIES, 



in masses ; the smaller are ovoid, and contain a single macro- 

 spore. 



1 O6. Salvinia (Fig. 30), recently discovered in Missouri, 

 has the sporocarps borne in clusters on short branches of the 

 floating stem, one or two of each cluster bearing ten or more 

 macrosporangia, each of which contains a single macrospore, 

 the remainder bearing numerous globose microsporangia with 

 numerous microspores. 



1O7. Germination. In Marsilia the antherozoids are 

 produced in a rudimentary prothallium which develops from the 

 microspore and are corkscrew-shaped, consisting of several 

 coils. The prothallium, developed from the apex of the ma- 

 crospore is a hemispherical mass of tissue, and contains a sin- 

 gle archegonium. Much is yet to be learned of the habits and 

 life-history of our native species. 



LITERATURE. 



BAKER (J. G.). Fern Allies, pp. 134-149 (1887). 



BRAUN (Alexander). On the North American Species of 

 Isoetes and Marsilca. In Sillimans Journal, Second Series, 

 ill, 52-56 (1847). 



Ueber Marsilia und Pilularia. In Monatsberichte dcr 



Ko'nigl. Akademie der Wissenschaft zu Berlin, 1863, 413-436. 



- Neuere Untersuchungen iiber die Gattungen Marsilia 

 und Pilularia. Ibid., 1870, 653-753. 



Nachtragliche Mittheilungen iiber die Gattungen Mar- 

 silia und Pilularia. Ibid., 1872, 635-679. 



ENGELMANN (George). New Species of Marsilia. In Stl/t- 

 maris Journal, Second Series, vi (1848). 



STRASBURGER (L.). Ueber Azolla. 8vo, 7 plates. Jena 



(1873). 



UNDERWOOD (L. M.) and COOK (O. F,). Notes on the 

 American Species of Marsilia. In Torrey Bulletin, xiv, 89-94 

 (May, 1887). 



